NCERT Class 11 Geography Part 1 Chapter 3: Interior of the Earth YouTube Lecture Handouts

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NCERT Class 11 Geography Part 1 Chapter 3: Interior of the Earth

Only Indirect Evidences

  • Exogenic + Endogenic forces = Shaping of landform
  • Earth radius = 6730 km (centre can՚t be reached)
  • Knowledge of interior based on estimate and inference (direct observation & analysis)
  • Matter from mining (temp. , pressure & density )
  • Meteors reaching earth
  • Gravitation (more near poles) , magnetic field (magnetic material in crust) , and seismic activity

Direct Sources

  • Deep mines (gold mines – 3 to 4 km)
  • “Deep Ocean Drilling Project” and “Integrated Ocean Drilling Project”
  • Deepest drill – Kola, Arctic Ocean 12 km deep
  • Volcanic eruptions – magma

Earthquakes -

Earthquakes
  • Shaking of earth
  • Natural event
  • Release of energy from waves
  • Along faults – break in crustal rocks, move in opposite direction
  • Seismograph – record waves reaching surface
  • Body waves – through body & interact with surface – are P & S waves
  • Surface waves – move along surface

Earthquakes Shadow Zones

Earthquakes Shadow Zones for Geography

Types of Earthquakes

  • Tectonic – Sliding of rocks
  • Volcanic – near volcanoes
  • Collapse – intense mining activity
  • Explosion – explosion of chemical or nuclear device
  • Reduced induced – in areas of large reservoir

Measurement of Earthquakes

  • Richter Scale – magnitude (energy released during earthquake 0 - 10)
  • Mercalli – intensity (visible damage 1 - 12)

Effects of Earthquakes

  • Ground Shaking
  • Differential ground settlement
  • Land and mud slides
  • Soil liquefaction
  • Ground lurching
  • Avalanches
  • Ground displacement
  • Floods from dam and levee failures
  • Fires
  • Structural collapse
  • Falling objects
  • Tsunami

Structure of Earth

Structure of Earth
  • Crust: Outermost (oceanic is thinner 5 km & continental is 30 km) - mean density of oceanic crust is 2.7 g/cm3
  • Mantle: from Moho till 2900 km; upper part is asthenosphere, higher density; lower mantle is solid
  • Core: Outer is liquid & inner is solid. Density is 5 g ⁄ cm3 and at centre it is 13 g ⁄ cm3, NIFE

Volcanoes

Volcanoes
  • Gas, ash & lava escape to ground
  • From asthenosphere – molten magma arises – lava

Types of Volcanoes

  • Shield: Largest, Hawaiian, Basalt & fluid, not steep, low explosivity
  • Composite: Eruption of cool & viscous lava, pyroclastic material and ashes, explosive eruption
  • Caldera: most explosive, collapse themselves and form calderas
  • Flood basalt province: Fluid lava to long distances (kms) , Deccan Trap covers Maharashtra Plateau
  • Mid-Oceanic Ridge volcano: oceanic area, central fissure with frequent eruption

Intrusive Volcanic Landforms

  • Volcanic: Cool at surface
  • Plutonic: Cool in crust
  • Batholith
  • Laccolith
  • Lapolith
  • Phacolith
  • Sill
  • Sheet
  • Dyke
Intrusive Volcanic Landforms for Geography

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